The invention relates to an apparatus for floor cleaning according to the preamble of claim 1.
Such apparatuses can be arranged in particular as scrubbing vacuum machines. One or several cleaning brushes act upon the floor surface to be cleaned. Cleansing liquid is sprayed onto the floor surface in the zone of the cleaning brushes and thereafter removed again from the floor surface with the extracted dirt under the influence of a suction apparatus and transferred to a dirty-water collecting vessel.
An apparatus for floor cleaning of this kind is known from DE 197 52 450 A1 for example. Swivelably front and rear wheels are provided on a frame. A circular brush is attached between the front and rear axle which are formed by the wheels. The known apparatus has the disadvantage that when moving around contours, e.g. shelves in supermarkets and the like, a relatively large surface area of the floor is not covered by the cleaning brush. It is necessary to subsequently clean the remaining uncleaned areas again.
In order to remedy the aforementioned disadvantage a floor cleaning device is proposed in DE 42 30 196 in which an additional brush device is provided which can be swiveled out laterally. The provision of such an additional brush device increases the weight of the apparatus, has a negative effect on its versatility and causes costs.
A floor cleaning device is known from DE 196 44 570 A1 in which merely one axle with two wheels is provided. A part of the weight of said floor cleaning device acts on a circular brush disposed in front of the axle. The apparatus is difficult to handle.
A floor cleaning device is known from U.S. Pat. No. 1,472,208 in which two rigid front casters and a swivelable rear caster are attached to a frame. A cleaning device is received on the frame between the front and rear casters. During curve movements, an axis of the momentary center of the curve movement, i.e. the so-called momentary center axis, which extends through the rigid front casters is far outside of a cleaning surface as defined by the cleaning device. When moving around edges there is always a transversal movement of the cleaning device. Uncleaned residual surfaces remain.
A further floor cleaning device is known from DE 41 03 087. A momentary center axis extending through the rigid front wheels intersects the cleaning surface. It does not intersect the cleaning surface in the zone of a circumferential edge of the cleaning surface which is located in the zone of the longitudinal side of the frame. Transversal movements of the cleaning device also occur in this floor cleaning device during curve movements. Uncleaned residual surfaces also remain in this case as well.
It is the object of the invention to eliminate the disadvantages according to the state of the art. An apparatus for floor cleaning is to be provided in particular which is easy to handle. Furthermore, the surface areas remaining when moving past contours are to be as small as possible.
This object is achieved by the features of claim 1. Appropriate embodiments are obtained from the features of claim 2 to 17.
It is provided within the terms of the invention that the momentary center axis forms at least one point of intersection with a section of the circumferential edge which is disposed in the zone of the longitudinal side of the frame.
The momentary center is understood as being a pole, i.e. a static point, about which a leg of a trajectory can be performed with the apparatus. In apparatuses for example with a rigid rear axle and swivelable or steerable front wheels, all momentary centers are disposed on the rear axle or an imaginary lateral extension thereof. A momentary center axis is defined by all momentary centers of an apparatus.
A cleaning surface of the apparatus is defined by the rotating cleaning means, e.g. the circular brushes. The cleaning surface is delimited by a circumferential edge. A section of the circumferential edge can be limited by the longitudinal side of the frame. A section of the circumferential edge is located in the zone of the longitudinal side of the frame when the momentary center axis intersects a lateral 45xc2x0 sector of the circumferential edge.
With the apparatus in accordance with the invention the swinging out of the front or the rear while moving past contours is avoided. The portion of uncleaned residual surface areas and the passage width can thus be kept to a minimum. The apparatus is easy to handle.
According to a preferable feature of the embodiment the momentary center axis extends in the vicinity of the vertical projection of the center of gravity of the apparatus. At least one non-steerable wheel can be attached on the momentary center axis close to the vertical projection of the center of gravity. Moreover, at least two, but preferably four swivelable and steerable wheels can be attached to the frame. Such an apparatus is particularly easy to handle and tilt-resistant.
According to a further embodiment two driven wheels are arranged on the momentary center axis. In this case the driven wheels can be driven with a different speed and/or in different directions of rotation. This variant is also characterized by versatility and ease of handling capability, particularly where riding apparatus are concerned.
It is provided according to a further embodying feature that at least one steerable wheel is attached to the frame. It is understood that also several steerable wheels could be provided. If steerable front and rear wheels are provided which are not disposed on the momentary center axis, the steering of the front and rear wheels must be performed in such a way that their axes always intersect on the momentary center axis when turning the wheels during steering.
The cleaning device is appropriately provided with at least one, preferably two or three, circular brushes, or at least one cleaning roller.
It is regarded as being particularly advantageous that a supply unit which is arranged as an exchangeable module comprises a tank, a dirt receiving device and a power supply unit. The module can be removed from the frame with ease by using a suitable docking station. Operating material can be added in the docking station, the power supply unit can be recharged and the dirt-water receiving device can be emptied. In order to ensure uninterrupted continuation of the work, the module can be exchanged for one with fresh operating material. An apparatus of this kind in combination with one or several features as set out in this paragraph can form per se a separate invention.
Preferably, the at least one non-steerable wheel is attached vertically movable relative to the swivelable wheels on the frame. For this purpose the at least one non-steerable wheel can be received in a lifting apparatus. It can concern, for example, a resiliently held rocker, a spring or a parallelogram-like lifting apparatus. It has further proven to be advantageous that a device is provided for setting the distribution of the load among the at least one non-steerable wheel and the swivelable and steerable wheels. The aforementioned features contribute further to the easy handling capability of the apparatus and the adjustment to the different permissible surface loads of the floor.
It is appropriate that a motor for driving the at least one driven wheel is attached to the frame. When the module is removed it is not necessary to additionally remove the motor from the frame.
It is further appropriate when at least one stop wheel is provided on a lateral brush cover. The apparatus can thus be guided without any frictional losses along a wall for example or precisely about a contour such as a corner or an edge. The stop wheel can be arranged with an axial offset xcex94y in front of the momentary center axis, with the following applying:
xcex94y=a Dbrush diameter
with a being capable of assuming values from 0.15 to 0.35 and Dbrush diameter being the diameter of the brush. It has proven to be particularly advantageous to use a value of 0.25 for a. If several stop wheels are provided one after the other on the lateral brush cover, it is necessary, with respect to the axial offset xcex94y, to consider the distance of a central axis defined by the central points of the stop wheels towards the monopole axis. The central axis extends parallel to the monopole axis and intersects a connecting line between the central points in the middle which are farthest away from one another.
According to a further embodiment, a housing contour in the zone of the cleaning device is disposed at least over sections on the circumference of a circle imagined about a central momentary center. This facilitates in particular the driving around edges, and the driving over edges.
It has proven to be particularly advantageous that the at least one point of intersection is disposed on an outermost lateral section of the circumferential edge preferably projecting beyond the longitudinal side of the frame. In this case there is no transversal movement of the cleaning device during a curve movement. The cleaning surface area can be guided with high precision along the contours. Corners can be cleaned substantially, so that the portion of uncleaned residual areas is minimal.